src/extras/rebase.js

   1 /**
   2  * @license
   3  * Copyright 2015 Petr Shevtsov (petr.shevtsov@gmail.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  *
   6  * Rebase plugin
   7  *
   8  * On pan/zoom event, each series will rebase to a specified value (e.g. 100) at the
   9  * start of the displayed period.
  10  *
  11  * See http://stats.oecd.org/glossary/detail.asp?ID=2249
  12  *
  13  * Options:
  14  *  Value to rebase. Must be either Number or 'percent' or null.
  15  *
  16  * See tests/straw-broom.html for demo.
  17  */
  18
  19 /*global Dygraph:false */
  20
  21 (function() {
  22
  23   "use strict";
  24
  25   // Matches DefaultHandler.parseFloat
  26   var parseFloat = function(val) {
  27     if (val === null) return NaN;
  28     return val;
  29   };
  30
  31   Dygraph.DataHandlers.RebaseHandler = function(baseOpt) {
  32     this.baseOpt = baseOpt;
  33   };
  34
  35   var RebaseHandler =  Dygraph.DataHandlers.RebaseHandler;
  36   RebaseHandler.prototype = new Dygraph.DataHandlers.DefaultHandler();
  37
  38   RebaseHandler.rebase = function(value, initial, base) {
  39     if (base === "percent") {
  40       return (value / initial - 1) * 100;
  41     }
  42     return value * base / initial;
  43   };
  44
  45   RebaseHandler.prototype.getExtremeYValues = function(series, dateWindow, options) {
  46     var minY = null, maxY = null, y;
  47     var firstIdx = 0, lastIdx = series.length - 1;
  48     var initial = series[firstIdx][1];
  49
  50     for (var j = firstIdx; j <= lastIdx; j++) {
  51       if (j === firstIdx) {
  52         y = (this.baseOpt === "percent") ? 0 : this.baseOpt;
  53       } else {
  54         y = RebaseHandler.rebase(series[j][1], initial, this.baseOpt);
  55       }
  56       if (y === null || isNaN(y))
  57         continue;
  58       if (maxY === null || y > maxY) {
  59         maxY = y;
  60       }
  61       if (minY === null || y < minY) {
  62         minY = y;
  63       }
  64     }
  65     return [ minY, maxY ];
  66   };
  67
  68   RebaseHandler.prototype.seriesToPoints = function(series, setName, boundaryIdStart){
  69     var points = [];
  70     var firstIdx = 0;
  71     var lastIdx = series.length - 1;
  72     var initial = series[firstIdx][1]; // TODO: check for null
  73     for (var i = 0; i <= lastIdx; ++i) {
  74       var item = series[i];
  75       var yraw = item[1];
  76       var yval = yraw === null ? null : parseFloat(yraw);
  77       if (yval !== null) {
  78         if (i === firstIdx) {
  79           yval = (this.baseOpt === "percent") ? 0 : this.baseOpt;
  80         } else {
  81           yval = RebaseHandler.rebase(yval, initial, this.baseOpt);
  82         }
  83       }
  84       var point = {
  85         x: NaN,
  86         y: NaN,
  87         xval: parseFloat(item[0]),
  88         yval: yval,
  89         name: setName,
  90         idx: i + boundaryIdStart
  91       };
  92       points.push(point);
  93     }
  94     this.onPointsCreated_(series, points);
  95     return points;
  96   };
  97
  98   Dygraph.Plugins.Rebase = (function() {
  99     var rebase = function(baseOpt) {
 100       var isNum = function(v) {
 101         return !isNaN(v) && (typeof v === 'number' || {}.toString.call(v) === '[object Number]');
 102       };
 103       if (baseOpt === "percent" || isNum(baseOpt)) {
 104         this.baseOpt_ = baseOpt;
 105       } else {
 106         this.baseOpt_ = null;
 107       }
 108     };
 109
 110     rebase.prototype.toString = function() {
 111       return "Rebase Plugin";
 112     };
 113
 114     rebase.prototype.activate = function(g) {
 115       if (this.baseOpt_ === null) {
 116         return;
 117       }
 118       return {
 119         predraw: this.predraw
 120       };
 121     };
 122
 123     rebase.prototype.predraw = function(e) {
 124       var g = e.dygraph;
 125
 126       if (this.baseOpt_ === "percent") {
 127         g.updateOptions({
 128           axes: {
 129             y: {
 130               axisLabelFormatter: function(y) {
 131                 return y + '%';
 132               },
 133               valueFormatter: function(y) {
 134                 return Math.round(y * 100) / 100 + '%';
 135               }
 136             }
 137           }
 138         }, true);
 139       }
 140
 141       g.dataHandler_ = new Dygraph.DataHandlers.RebaseHandler(this.baseOpt_);
 142     };
 143
 144     return rebase;
 145   })();
 146 })();